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1 | /* xalloc-oversized.h -- memory allocation size checking |
2 | ||
ba318903 | 3 | Copyright (C) 1990-2000, 2003-2004, 2006-2014 Free Software Foundation, Inc. |
73dcdb9f PE |
4 | |
5 | This program is free software: you can redistribute it and/or modify | |
6 | it under the terms of the GNU General Public License as published by | |
7 | the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
17 | ||
18 | #ifndef XALLOC_OVERSIZED_H_ | |
19 | # define XALLOC_OVERSIZED_H_ | |
20 | ||
21 | # include <stddef.h> | |
22 | ||
23 | /* Return 1 if an array of N objects, each of size S, cannot exist due | |
24 | to size arithmetic overflow. S must be positive and N must be | |
25 | nonnegative. This is a macro, not a function, so that it | |
26 | works correctly even when SIZE_MAX < N. | |
27 | ||
28 | By gnulib convention, SIZE_MAX represents overflow in size | |
29 | calculations, so the conservative dividend to use here is | |
30 | SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value. | |
31 | However, malloc (SIZE_MAX) fails on all known hosts where | |
32 | sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for | |
33 | exactly-SIZE_MAX allocations on such hosts; this avoids a test and | |
34 | branch when S is known to be 1. */ | |
35 | # define xalloc_oversized(n, s) \ | |
36 | ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n)) | |
37 | ||
38 | #endif /* !XALLOC_OVERSIZED_H_ */ |